Field of the Invention
The present invention relates to an image processing apparatus that determines whether image data is data obtained by reading a page containing printing information or data obtained by reading a blank page having no printing information.
Description of the Related Art
For image reading apparatuses such as a digital copying machine, mainly two types of document reading techniques are available. One technique is reading an image by placing a document on a platen glass and moving an optical system while fixing the position of the document (an optical-system moving method). The other technique is reading an image by conveying a document with an auto document feeder (ADF) while fixing the position of an optical system (a feeding-reading method).
A conventional multi-function peripheral apparatus equipped with an automatic document scanner reads both sides of a sheet even when double-sided printed documents and single-sided printed documents are mounted in a mixed manner.
However, in this method, a blank page on the back of the single-sided printed document is also read. Therefore, unnecessary data is processed, which reduces a processing speed. In addition, print processing is executed also on image data generated by reading the blank page when the read document is output, which causes unnecessary paper consumption and power consumption. Therefore, unnecessary printing, paper, and toner consumption can be suppressed by using blank page detection, thereby removing image data determined to be the image data obtained by reading the blank page. Further, in a case where the obtained data is transmitted as electronic data such as an e-mail, file capacity can be suppressed by removing the image data determined to be the image data obtained by reading the blank page. Therefore, various types of blank page detection methods have been devised (see Japanese Patent Application Laid-Open No. 11-55503).
Japanese Patent Application Laid-Open No. 11-55503 discusses a blank page determination method. This method detects an edge portion from image data read from a document, and determines whether the document is a blank page, based on a ratio of an amount of the detected edge portion to the total number of pixels.
Japanese Patent Application Laid-Open No. 2008-219808 discusses a method for detecting a blank page. Specifically, this method determines whether a document is a color background document or white background document, and changes a determination criterion for detecting blank page if image data obtained by reading the document is determined to be image data obtained by reading a color background document. Thus, when the color background document includes a blank page, this blank page is detected.
However, a document to be detected as a blank page may vary according to usage intended by a user.
For example, assume that a piece of colored paper having a background color other than white is inserted as a slip sheet into documents each having a background color of white and containing printing information. In this case, it may be desirable to detect and remove image data obtained by reading a blank page included in the white background documents. However, it may be desirable to output image data obtained by reading blank pages of the colored paper, as the slip sheet. Further, it may be desirable to detect and remove image data obtained by reading the colored paper inserted as the slip sheet, without removing the image data obtained by reading the blank page included in the white background documents to maintain a layout.
In this way, depending on the usage intended by the user, the image data obtained by reading the blank page may not be the data desired to be removed. That is, the image data desired to be removed may vary according to the background color of the blank page (document).